Charge forming method and apparatus for internal-combustion engines



Oct. 22, 1946. G BODINE 2,409,611

CHARGE FORMING METHOD AND APPARATUS FOR INTERNAL-COMBUSTION ENGINES-Filed Oct. 17, 1939 3 Sheets-Sheet 1 Fi .1. a

HARRIS, mac, F 0: r0? 3 HAP/PAS F P 7W5 FIRM A rrgmvz s.

Oct. .22, 1946. G; B DlNE 2,409,611

CHARGE FORMING METHOD AND APPARATUS FOR INTERNAL-COMBUSTION ENGINESFiled Oct. 17, 19:9 2 Sheets-Sheet 2 JNVENTOR BY ALBERTG. Boo/Ms HARRIS,Kmch; Fos r51? & H4225 FOR mil-TQM 2 1946 A..G. BODINE 2,409, 11 CHARGEFORMING METHOD AND APPARATUS FOR INTERNAL-COMBUSTION ENGINES Filed Oct.17. 1939 5.Sheets-Shet 5 figs f/wE/v T01? ALBERT 6. BUD/NE Patented Oct.22, 1946 TUS GIN ES FOR INTERNAL-COMBUSTION EN- Albert G. Bodine, LosAngeles, Calif.

Application October 1'7, 1939, Serial No. 299,830

17 Claims. 1 This invention relates to fuels and fuel systems andrelates more particularly to high vapor pres sure fuels and to apparatusadapted to supply such fuels to internal combustion engines, includingcarburetors and storage tanks.

Fuels for internal combustion engines are conventionally of the Dieseltype, gasoline type, or gaseous type. This invention is concerned withthe composition of and methods for handling a still further type of fuelwhich in some respects is intermediate in characteristics betweengasoline and gaseous fuels.

As a general rule, gaseous fuels such as methane, ethane, propane andbutane possess many advantages over the gasoline type of fuel, forexample, an inherently very much higher knock rating, cleaner operation,and less tendency to form carbon deposits, avoidance of fuelcondensation in the manifold and combustion chamber, absence ofcrankcase dilution, and the like.

These advantages inherent in the gaseous fuels have hitherto, however,been oifset by decreased mobility and simplicity of equipment, increasedbulk and weight of storage containers for the fuel, and the like.Gasoline has hitherto represented the most volatile fuel that could beconveniently handled, stored in storage vessels of reasonable weight,and accurately metered in the liquid phase in carburetors at atmosphericpressures. H In connection with the use of gaseous fuels, stationaryengines which are located near a source of natural gas may use this gaswithout much difiiculty, but with engines remote from suitable sources,and more particularly with mobile engines for use in automobiles,trucks, aircraft, and the like, it is necessary that the gaseous fuel betransported. For such purposes propane or butane is usually used, beingliquefied by the imposition of suificient pressure and being stored inthe liquid condition in heavy metal containers or cylinders of adequatestrength to safely resist the pressures involved. In use the liquidmaterial is drawn from such a container as needed, heated above itsflash distillation temperature to convert it into a vapor, passedthrough a pressure reduction valve to obtain the gas at suitablepressure, and then admixed with combustion air in a suitable carburetor.1

Such equipment is very bulky and weighty and is difficult to handle andkeep in adjustment. The natural vapor pressure of liquefied propane orbutane imposes requirements for strength and Weight on the storagesystem that mitigate against the use of such systems in anythingbut veryheavy duty equipment such as trucks. It is difficult to keep thecarburetor in proper adjustment for a variety of reasons, including thefact that the proper metering of the gasified fuel depends not only onthe pressure, but on other factors suchas the temperature whichinfluences the density of the gasified fuel. Furthermore, the use of acompletely gasified fuel for carburetion involves a certain loss involumetric efiiciency, as contrasted with a liquid fuel.

It is an object of the present invention to provide a fuel having asubstantially higher vapor pressure than gasoline and which approachesor equals pure propane or butane as regards the inherent advantages ofsuch normally gaseous fuels, having particular reference to suchadvantages as high knock rating, enhanced ignition range, cleanoperation, lack of carbon deposits, absence of condensation in manifoldsand crankcases, and light density. This fuel is so composed (suitably bythe addition of a small amount of modifying agent to a propane or butanebase, or by the addition of any normally gaseous fuel to a normallyliquid and substantially less-volatile fuel) that the vapor pressure ofthe resultant product is substantially less than that of liquid proponeor butane, whereby very much lighter storage vessels may be used and theincidental equipment lightened and simplified.

It is also an object of the present invention to provide carburetors inwhich high vapor pressure fuels such as the above and others may bemetered under pressure and in the liquid phase, and injected directly asa liquid into the intake manifold or combustion cylinder.

It is also an object of the present invention to provide improvedstorage vessels for high vapor pressure fuels of the above type andother types, including storage vessels in which provision is made forautomatic internal refrigeration to minimize the storage pressure.

Various other objects and aspects of my inven tion Willbecome apparentin the following dis- 3 vessel and fuel system adapted to automaticallymaintain the contents of the storage tank below any desired pressure byautomatic internal refrigeration.

Fig. 5 is a cross-sectional view of another storage tank and fuel systemproviding automatic internal refrigeration in response to thedevelopment of excessive pressure.

Fig. 6 is a diagrammatic view showing the carburetor of Fig. 2 in itsrelationship with a fuel storage tank.

Fig. '7 is an alternative embodiment of the carburetor shown in Fig. 1.

Fig. 8 is an alternative embodiment of the carburetor shown in Fig. 2.

Referring more particularly to Fig. 1, i is an induction pipe forsupplying air and fuel to the intake manifold of an internal combustionengine. The induction pipe E6 is provided with a venturi I I, abutterfly throttle valve l2, and an open end in communication with theatmosphere to supply an air inlet l3. Between the butterfly valve [2 andthe intake manifold of the engine, pipe I!) is provided with a threadedopening l4 into which is screwed a threaded member 15 which is integralwith a carburetor casing !B. The interior of the carburetor casing isdivided into compartments A, B, C, D, and E by means of diaphragms ll,18, i9, and 26 respectively. These diaphragms are all securely fixed to'and movable with a valve stem 25. The outer peripheries of all of thediaphragms are hermetically sealed to the carburetor casing H orabutments therefrom by means of flexible members Ila, iBa, 19a, and Zllarespectively. By means of these flexible members the valve stem 2| andthe entire assemblage of diaphragms are free to move as a unit for acertain limited vertical distance within the casing it while maintainingthe respective compartments sealed from one another.

The lower portion of valve stem 2! terminates in a conical valve member22. A valve seat 23 suitably constructed as a circular washer composedof a resilient hydrocarbon resistant material such as neoprene or othersynthetic rubber is supported on a re-entrant tubular member 24 whichmay be integral with the casing I6 and which provides a passageway 25 topermit the flow of fuel (metered by the discharge valve constituted bythe valve members 2'2 and 23) into the induction pipe iii. The valveseat 23 may be secured in position on the tubular member 24 by means ofa threaded collar 26.

Compartment A is in communication with a fuel chamber 39 suitablyconstructed as a small chamber in the carburetor casing l6. Aconstriated orifice or pilot jet 3! is placed between compartment A andthe chamber 30 to limit the communication therebetween to apredetermined value.

Compartment B is also in communication with the chamber 30 by means of apassageway 32 which affords little or no restriction to freecommunication. A nipple 33 connects the chamber 30 to a T-member 34, onebranch of which is connected to a suitable source of fuel supply (notshown), and the other branch of which is in open communication by meansof tubing 35 with the upper compartment E.

Compartment D communicates by means of tubing ill with the venturi l Iso that the suction of the venturi, which is proportional to the masstravel of air therethrough, is transmitted to compartment D. a

Compartment C is tapped by one leg of a hollow T 45, the second leg ofwhich is closed by a plug 46 having a small hole therethrough to serveas an air bleed. The third leg of the T d5 communicates by means oftubing 41 with the pipe [0 at a point downstream from the venturi. Ihiscommunication is preferably effected through an impact scoop 48 havingan open end facing upstream so that the pressure received andtransmitted by the member 48 and tubing ll to compartment C representsnot only the static pressure in the induction pipe H], but also thedynamic pressure due to the mass velocity of the fuel-air mixtureflowing through the pipe I9. If desired, however, compartment C may beallowed to communicate directly with the atmosphere as by the removal ofthe plug 46, in which instance tubing 4'! may be suitably blanked off,and the butterfly I2 moved to a zone between the venturi H and theorifice 25, all as shown in Fig. 7.

The operation of this device is as follows. A suitable liquid fuel issupplied to the carburetor under pressure. Such a fuel is preferably aliquefied high vapor pressure fuel such as is described elsewhere in thespecification, although this is not essential for the functioning of thecarburetor and it may operate, for example, on gasoline delivered at asuitable pressure by means of a pump, or it may also operate on veryhigh vapor pressure fuel such as pure liquefied pro ane. Due to the freecommunication between the T- member 34 and compartments E and B, thelatter via the chamber 3|], these two chambers are at full fuelpressure. Compartment A is delivering fuel to the induction pipe l0through the valve means 22 and the attendant flow of liquid fuel fromthe chamber 39 to compartment A past the pilot orifice 3| causes apressure drop across this orifice so that the pressure in compartment Ais less than that in compartment B by an amount which is proportional tothe rate of fuel flow through the pilot orifice 3!. This unbalance ofpressure across the diaphragm ll tends to move the diaphragm and valvestem 2i downwardly, or, in other words, tends to close the valve means22. This tendency to close the discharge valve is offset by balancedforces in the opposite direction, as will presently be made clear.

The butterfly valve l2 being open at least par tially, the intake airflows through the venturi i l thus creating a suction which istransmitted to compartment D. For the moment it may be assumed thatcompartment C is freely open to the air and hence at atmosphericpressure. The pressure in compartment D is hence less than that incompartment C by an amount which is proportional to the Venturi suction.This. produces an unbalance of pressure across the diaphragm [9 whichtends to move it upwardly and to open the discharge valve.

The discharge valve is thus subject to two opposing forcesone whichtends to open it and which is proportional to the rate of air flowthrough the venturi, and the other which tends to close it and which isproportional to the rate of fuel flow into the induction pipe IE3. Ifthe closing force is the greater, the entire valve stem and diaphragmassemblage moves downwardly, thus tending to close the discharge valveas defined by the valve elements 22 and 23. This has the immediateeffect, however, of decreasing the rate of fuel flow through thedischarge valve and hence the rate of fuel flow through the restrictedorifice or pilot jet 3|. The pressure drop across this orifice 3| isimmediately decreased and hence the unbalance in pressure betweencompartments A and'B is decreased and, in fact, brought to a point suchthat the closing force becomes equal to the opening force. The dischargevalve then remains stable at this setting provided no other factors arechanged. If the opening forces are at any time greater than the closingforces, it may be similarly shown that the discharge valve will beopened to a new equilibrium setting in which the opening and closingforces are balanced.

At this balanced setting of the discharge valve the closing force, whichis proportional to the rate of fuel flow, is equal to the Opening force,which is proportional to the rate of air flow, and thus proportionalityis at all times established between the rates of fuel flow and the ratesof air flow so that a proper mixture of air and fuel may be had underall conditions.

In the final analysis, the entire system is responsive to the setting ofthe butterfly or throttle valve since this determines the rate of airflow through the venturi, which in turn determines The proportionalityconstant between fuel rates and air rates which determines thecomposition of the combustion mixture is best adjusted by variations inthe size of the restricted pilot orifice 3|. If desired, this restrictedorifice may be constructed as a manually adjustable needle valve so thatthe proper setting for mixture may be readily obtained.

Further factors are involved in the operation of the carburetor whichare concerned principally with the balance of the minor forces set upacross the diaphragms l8 and 2B and With suitable provision for idling.The unbalance across the diaphragm l8, which is proportional to thedifference between fuel pressure and atmospheric pressure, is slightlymore than counteracted by the unbalance across the diaphragm 20, whichis proportional to the difference between fuel pressure and Venturipressure. The forces involved here are relatively small, however, inview of the relatively small surface areas of these diaphragms, and aslight'bias in one direction or another does not introduce anysubstantial deviation in the desired proportionality between air andfuel flow. In some instances it is desirable to provide a slight closingbias to insure the secure closure of the discharge valve when the engineis not in operation, and this may be readily done, for example, byinserting a light spring 49 between diaphragm l9 and the top portion ofthe carburetor shell It.

In the above description of operation it was assumed that compartment Cwas open directly to the atmosphere and under these conditions thequestion of idling Was not discussed nor would suitable idlingconditions be directly available. Many engines, however, notablyairplane engines, are never run under idling conditions, but, ifdesired, conventional idling means may be employed.

The best method for control of idling conditions, however, is affordedby use of the means denoted by the numerals 45, 46, 41, and 48, and thismeans is furthermore effective in enrichening the mixture in fullthrottle operation, such enrichening being frequently very advantageous.

The operation of the above indicated means is as follows. When thebutterfly valve i2 is closed or in idling position, a very low absolutepressure prevails in the induction pipe Hi. This low static pressure istransmitted virtually unchanged through the-tubing M! to compartment.

the rate of fuel injection into the induction pipe 6 D, the venturieffect under these conditions being very small due to the negligibleflow of air. Compartment C is also in communication with the pipe in bymeans of the tubing 41 and scoop 4B but due to the small air bleed inthe plug 46, which permits a small stream of air to enter the tubing 41under the high pressure differential that exists under these conditions,the effective pressure in compartment C is somewhat higher than incompartment D. .As a result, there is a small opening force on thediaphragm l9 which keeps the discharge valve slightly open so that anamount of fuel suitable for idling is discharged into the induction pipeIn. As before, the flow of fuel sets up a resultant small closing forceacross the diaphragm ll which balances the opening force and keeps thedischarge valve stabilized at a suitable idling opening. A suitableidling mixture may be obtained by appropriate adjustment of the airbleed in the plug 46.

This device also serves to gradually enrich the mixture as the butterflyvalve 12 is opened. For example, when the butterfly valve I2 is fullyopened, the static pressure in the induction pipe to is approproximatelyatmospheric and this atmospheric pressure is transmitted by means of thescoop A8 and tubing 41 to compartment C. An additional dynamic pressureis also transmitted to compartment C, this dynamic pressure having itssource in the impact of the rapidly moving charge in the pipe if! on theupstream opening in the scoop 48. This additional dynamic pressure incompartment C creates an additional force tending to open the dischargevalve, thus resulting in a richer mixture. The degree of this enrichmentdue to dynamic pressure is proportional to the setting of the butterflyvalve I2, which determines the mass velocity of the flow through theinduction pipe IE3 and is hence greatest under full throttle operationin which the enrichened mixture is especially desirable for purposes ofincreased acceleration and power.

Referring more particularly to Fig. 2, is an induction pipe adapted tosupply the fuel-air charge to the intake manifold of an engine, thisinduction pipe ti! being provided with a butterfly valve 6!, a venturi62, and an air inlet 63 (suitably the open end of pipe 60). The venturiis supplied with a lateral tap or jet 64. An opening is provided in theinduction pipe 60 downstream from the butterfly valve, in which openingis snugly fitted an L-shaped tubular member provided with a shoulder 65which abuts against the interior wall of the pipe 60. The member 65continues exterior of the pipe iii) with a threaded portion 61 which isscrewed into a re-entrant tubular member 63 integral with a carburetorcasing 69. The tubular L-shaped member 65 is so arranged and dimensionedthat it is adapted to receive the fuel discharged from the carburetorcasing and transmit it to the open end 153 which faces downstream and ispositioned approximately coaxially with the pipe 69.

The interior of the carburetor casing 89 is divided into twocompartments F and G by a diaphragm 15 sealed to the casing 69 by meansof a flexible member 15a.

The diaphragm 15 is securely fixed to a valve member 16 which is therebyconstrained to move with the diaphragm. The lower portion of the valvemember 16 terminates in a conical member which cooperates with a valveseat I! to form a discharge valve. The Valve seat Ti is securely mountedon the upper end portion of the re- '7 entrant tubular member threadedcollar 18.

A primary fuel is supplied to compartment G through a jet or restrictedorifice shown as an adjustable but always open needle valve 80. Asecondary fuel is supplied to compartment F by means of a jet orrestricted orifice shown as an adjustable but always open needle valve8!. If desired, the secondary fuel supplied the adjustable needle valve8| may first be passed in heat exchange relationship with the liquid ormetal situated near the discharge valve as by means of a tubing 82.

It is required that the primary and secondary fuels he delivered to theneedle valves 80 and 8! at substantially the same pressure or at leastin some definite pressure relationship. The secondary fuel is preferablya liquid, suitably a high vapor pressure liquid fuel such as isdisclosed elsewhere in this specification. The primary fuel may beeither a liquid or a as. For example, both the primary fuel and thesecondary fuel may be constituted by the same liquid, for example,butane, which may be fed from a common line into needle valves 89 and 8!respectively. The primary fuel may very advantageously be a gaseousfraction derived from the high vapor pressure fuel. For example, theneedle valve 86 may be supplied from the gaseous phase in a fuel storagetank, and the valve 81 may be supplied from the liquid phase in the sametank. Suitable storage tank connections for such usage are indicated inFig. 3 and Fig. 6 discloses the complete combination, the storage tankbeing here indicated by the numeral 83, the upper end thereof beingconnected to the needle valve 80 by tubing 84 and the lower end beingconnected to the needle valve 8i by the tubing 82. Here, the inductionpipe 68 is shown as connected to a mani- 68 by means of a fold 85feeding the cylinders of an internal combustion engine 86.

If the primary fuel and the secondar fuel are delivered from storageunder substantially different pressures or if the pressure relationshiptherebetween is highly variable, a conventional pressure equalizingmeans may be used to bring the fuels to the same pressure or to adefinite pressure ratio before introducing them into the needle valves80 and BI.

The primary fuel introduced through the needle valve 89 into compartmentG is introduced into the induction pipe 68 at venturi 62 by means of thetap 64 acting as a jet. The primary fuel is conducted from compartment Gto tap 64 by means of a tubing 90 and various auxiliary means thecharacter of which will depend on the character of the primary fuel.Suitable auxiliary means for use in connection with a gaseous primaryfuel have been illustrated and include a conventional gas pressureregulator 9| and a cutoff valve 52. The gas regulator 9! reduces thepressure of the gaseous fuel to approximately at mospheric pressurebefore permitting it to be aspirated into the venturi. The cut-off valve92 is closed when the engine is not in use to prevent any leakage ofprimary fuel.

If the primary fuel is constituted by a liquid, the pressure regulator9| ma be replaced by a liquid regulator (suitably a float chamber) whichwill supply the liquid at a constant head, all as shown in Fig. 8.Alternatively, a vaporizing unit Sla may be placed ahead of theregulator 9! and the liquid primary fuel converted to gas beforesubmitting it to pressure regulation and injection into the venturi.

The operation of the carburetor shown in Fig. 2 is as follows. Themethods used to deliver the primary fuel from compartment G into theventuri are more or less conventional and it follows from the usualconsideration that the quantity of primary fuel thus introduced into theventuri is a function of the mass travel of air through the venturi sothat the desired proportionality between induced air and injectedprimary fuel is thus set up.

If it is assumed that the primary and secondary fuels are delivered tothe needle valves B!) and BI at the same pressure, which pressure willbe hereinafter referred to as storage pressure, then the pressure incompartment G is less than the storage pressure by an amount whichcorresponds to the pressure drop across the needle valve 80. Thispressure drop is a function of the rate of flow of the primary fuel andthe constants of this function may be varied by adjustment of the needlevalve 86.

The valve BI is constantly open an adjusted amount. However, in theabsence of an substantial flow of secondary fuel through the valve 8iand into compartment F, due to closing of valve i5, 71, the pressure incompartment F would be substantially storage pressure. Under theseconditions the pressure unbalance across the diaphragm '15 would causethe discharge nozzle to open, thus permitting flow of secondary fuelthrough compartment F and into the induction pipe Ell via member 65.This flow of secondary fuel results in a pressure drop across the needlevalve 8| which reduces the pressure in compartment F so that thediaphragm '15 will eventually come to rest at an equilibrium setting ofthe discharge valve such that the pressure drops across the two needlevalves become equalized. The rate of flow of secondary fuel is thusproportional to the rate of flow of primary fuel and both areeffectively controlled by the rate of air travel through the venturi sothat the desired relationship between total air induction and total fuelinduction is thus had. lihe relative proportions of primary andsecondary fuels may be adjusted to any desired value by suitable settingof valves 88 and/or 8|.

Differences in source pressure may also be taken care of by appropriateadjustment of the valves and 8! provided that under conditions of nofuel flow the discharge valve will remain stable in closed position. Itis frequently desirable to add a slight closing bias to the dischargevalve as by means of a pring 93 adapted to exert a slight closing forceon the diaphragm 15. This is not only of value in insuring the closureof the discharge valve when the engine is not in operation, but it alsoinsures that the primary fuel forms the principal constituent of thecombustion mixture at very slow rates of operation. At low idling speedsthe Venturi aspiration is a somewhat more accurate metering means thanis the diaphragm-operated discharge valve.

In some respects I consider the carburetor shown in Fig. 2 as preferableto that in Fig. 1. It is more simple in construction and offers lessproblems in valve and diaphragm alignment. Furthermore, the Venturimetering at low fuel rates is a much more sensitive method of control inidling or low speed operation than is the control of the discharge Valveby the restricted orifice 3! of Fig. 1. The use of two fuels also offersgreat flexibility of operation since one of the fuels may even begaseous. A safety factor is also present in the operation of thecarburetor shown i Fig. 2 since even if the secondary fuel systembecomes clogged or inoperative, low power motor operation can still bemaintained on the primary fuel alone.

These are relatively small distinctions, however, in comparison to thevery important advantageous and novel characteristics which aredisplayed by both carburetors in common.

Both carburetors are insensitive to variations in pressure duringoperation. An increase in pressure of the fuel or fuels which aresupplied to the carburetor does not affect the metering. Also themetering remains unchanged by any variations in the pressure in theinduction piping into which the fuel is discharged.

This latter point is particularly important since it permits theinjection of the fuel into the manifold at a point downstream from thebutterfly valve. The pressure at this point downstream is variable butis usually substantially less than atmospheric. This relatively lowpressure or partial vacuum at the point of fuel discharge is of greatvalue in improving the rapid vaporization and dispersion of the fuelthroughout the air.

The tendency toward icing is also thereby decreased since partial vacuumeffects correspondare necessary to thus meter the liquids, the

metering being performed solely in response to the Venturi pressure.These carburetors may be aptly described as Venturi-controlled, injectortype carburetors adapted to operate under high pressures.

Another important feature is that the effective metering is done by thedischarge valve and at the point of discharge so that the metered liquidis immediately completely free to escape into the induction pipe. Thisis of particular advantage in using high vapor pressure fuels where theattempt to first meter a given quantity of the liquid and subsequentlyto discharge it through a pressure reduction valve may give rise to veryuneven discharge from such a pressure reduction valve due to partialvaporization and/or changes in pressure and temperature between themetering device and the final discharge valve.

Many other advantages are also present in my carburetors, among whichmay be mentioned the 'full closure of the discharge valve when theengine stops, even though the fuel may be under very high pressure, thecompletely enclosed character of the carburetors whereby extraneous matI ter is excluded, and the like. I

' The most important advantages of my carburetors become apparent,however, only when consideration is given to the question of fuel.Gasoline type carburetors, typically atmospheric pressure float-bowlcarburetors, can be used only in connection with gasoline type fuels, i.e.', fuels containing little or no normally gaseous constituents andhaving a vapor pressure not appre-,

carburetorsfor gaseous fuels are adapted to work on the fuel only afterit has been converted into the gaseou state, which requires that theliquefied gases used therewith, such as propane and combustion mixture.

butane, be substantially free from any heavier constituents which wouldnot volatilize or which would interfere with volatilization. 1

With my type of carburetor sufiicient pressure can be imposed to keepnormally gaseous constituents liquefied or in solution up to thedischarge or injection point. Since the fuel is injected as a liquidwithout the requirement of prior volatilization, the presence ofrelatively nonvolatile. constituents in the liquid fuel is completelyunobjectionable. Consequently, by the use of these carburetors therebecomes available for use ininternal combustion motors a whole new classof fuels, namely, those fuels which contain sufficient normally gaseousmaterials to have avapor pressure substantially in excess of atmosphericand which may contain in addition very substantial proportions of fuelconstituents whose vapor pressure is well below atmospheric or which arerelatively non-volatile. i i

The composition and characteristics of such mixed base fuels, i. e.,fuels containing constituents both of the normally gaseous and normallyliquid types, will presently be discussed in greater detail, but inconnection with the present question of carburetors, it is apparent thatsuch fuels could not be used in conventional type carburetors and becomeavailable for use only through the special characteristics of thecarburetors as above described.

Even when operating on a fuel containing only normally gaseousconstituents such as propane or butane or a mixture thereof, my. methodof carburetion presents great advantages over conventional. methodsinvolving ,vaporization. In the first place,..my methcdeliminates theneed for the bulky and difiicultly operable vaporizi units which havehitherto been necessary to convert all of the liquefied fuel into gas.,Inrny method neither pressure nor temperature variations are ofimportance whereasin the prior handling of completely gasified fuel. itwas necessary to maintain the density or the vaporizedjuel substantiallyconstant in order to obtain the proper This requirement of uniformdensity in-the gas mixture required the use of isobaric and thermostaticdevices to maintain the gas at constant pressure and temper,- ature, allof which become unnecessary in the present method. i A very importantadvantage accruing from my method of injecting the normally gaseous fuelconstituents in liquefied or dissolved form arises from the fact thattheir vaporization takes place in .direct heat exchange relationshipwith the combustion charge whereby the latent heat of vaporizationbecomes available for cooling of the charge with resultant increases in;volumetric efficiency. The effects of a supercharger are thus obtainedwithout any penalty of power diversion to a super-charging unit.

The direct exchange of the latent heat of vaporization with the sensibleheat of the charge results in very high cooling efficiency, much greaterthan can be obtained by methods of indirect heat exchange; My carburetoris of value, however, even if it is desiredto maintain an indirect heatexchange relationship between the vaporizingfuel and the induced air.For example, in Fig. 2 the tubular member may be extended as a; longductin. heat exchange relationship with the air moving through the pipe sothat the vaporization of the. fuel in the duct cools'the-air indirectly.The vaporized .fuel may :then be injected; into the combustion cylindersindependently of the air suitably by means of an injecting ordistributing system so that some further increase in volumetricefficiency may be obtained.

I prefer to use a portion of the latent heat of vaporization to cool thefuel charge in the carburetor and to prevent the premature gasificationof any portion of the fuel such as might tend to rise from the flow ofengine heat into the carburetor casing or from pressure reductionsincident to the transfer of the fuel from the storage tank to thecarburetor and the passage of the fuel through the pilot orifice. Thisis preferably accomplished by the use of a reentrant discharge duct suchas the tubular member 24 of Fig. 1 or tubular member 68 of Fig. 2. Therefrigeration at and immediately below the discharge valve thus becomesavailable for cooling the contents of the carburetor. This refrigerationmay also be very advantageously used to pre-cool the feed to thecarburetor, as is indicated by the tubular means 82 in Fig. 2. If suchpro-coolingof the feed and/or refrigeration of the carburetor is notemployed, it will usually be found necessary to employ a pump in thefuel transfer lines to build up the pressure to a value sufficient toprevent premature vaporization.

Many other advantages of my method of carburetion over the conventionaldry gas carburetion will be apparent to one skilled in the art, althoughspecific mention might here be made of the fact that my device iscompletely responsive to Venturi control and to Venturi mixing, whereasdry gas carburetors ordinarily require a mechanically movable valve toobtain fully eificient metering and mixing. Also, the severity ofbackfire is lessened in my device since I inject the main portion of thefuel downstream from the venturi and butterfly whereby the total volumeof inflammable material can be made materially less than in theconventional practice of introducing all of the fuel at the venturiand/or upstream from the butterfly valve.

Several features of importance arise in comparing my method ofcarburetion with that normally employed in gasoline injectioncarburetors. In conventional gasoline injection carburetors the fuel isjetted as a liquid directly into the moving air stream. In order toincrease the atomization and dispersion of the liquid fuel, use isusually made of a pulverizing nozzle or jet which tends in some degreeto give a finer comminution of the liquid droplets in the air. With mymethod atomization, disruption, and dispersion of the fuel in the airare automatically had to a very enhanced degree. Because of therelatively high pressure under which the fuel is maintained up to thepoint of discharge, a large amount of energy proportional to thepressure drop across the discharge nozzle becomes available fordisruption and atomization of the liquid fuel. Furthermore, immediatelythe liquid fuel containing normally gaseous constituents is released toatmospheric or sub-atmospheric pressures, a violent or explosive typeboiling takes place which serves in very marked degree to furtherdisrupt and atomize the remaining liquid.

This efiect is apparent even-though the remaining liquid contains asubstantial proportion of relatively non-volatile constituents.

Other advantages incident upon the injection of high vapor pressure fuelare as follows. The almost immediate vaporization of the normallygaseous constituents insures very early mixing of the fuel and the airin the carbureti-on system whereby a very homogenous air-fuel mixture isobtained. The distribution quality of such a mixture is particularlygood, each cylinderof the engine receiving a mixture of substantiallythe same composition.

The rapid volatilization of the normally gaseous constituents results ina lower temperature and increased density of charge mixture extendingback substantially to the point of injection. The desirable inertiaeffects of the moving charge are thereby increased, which efiects are inaddition to the above-mentioned increase in volumetric eiiiciency whichis attributable to the increased density per se.

Another eifect which becomes apparent when the high vapor pressureliquid is injected in a direction parallel to the air flow, orsubstantially parallel, as provided for in the curvature of pipe 10 ofFig. 1 and by the .L-bend in member 65 in Fig. 2, is the ramming orinspirating effect on the air and fuel in the induction pipe, whicheffect arises both from the kinetic energ of the discharge stream, andits relatively large area of effective contact with the gases in theinduction ipe as caused by the explosive gasification of the normallygaseous constituents immediately subsequent to injection, and whicheffect has as a consequence an inspirating eifect on air upstream fromthe point of injection and a ramming or supercharging effect on thefuel-air mixture downstream from the point of injection.

Fig. 3 is a cross-section of a flexible walled, vapor inflated fuelstorage vessel for use in connection with liquid fuels having high vaporpressure generally and more particularly in connection with my mixedbase, high vapor pressure fuels having vapor pressures in excess ofatmospheric but not extending substantially beyond 20 or 25 pounds persquare inch gauge at 70 This storage vessel has as its essential featurea closed or hermetically tight flexible envelope me which envelope isadapted to be inflated or distended and maintained in more or less rigidcondition by the vapor pressure of the liquid contents kept therein. Arigid framework, suitably of latticed construction, is preferablyprovided to partially enclose the envelope 00. A cross-section of such aframework is indicated in Fig. 3, [Bl denoting a rigid bottom support,H12 denoting a rigid top support, and m3 and HM denoting rigid sidemembers.

An outlet for the liquid content within the containing envelope IEZEJ isprovided by means of pipe I35 which extends upwardly through the bottomrigid member i6! and transpierces the envelope at this point. The upperportion of the pipe IE5 is provided with a collar Hi6 and this collar isbrought into sealing compression with the envelope I00 and the rigidmember iiil by means of an external lock nut I01 which is threaded onthe exterior portion of the pipe I05.

In case it is desired to withdraw gaseous fuel from the upper gas phasein the container H10 as when it is desired to use the gas as a primaryfuel in connection with a carburetor such as is shown in Fig. 2, a gasWithdrawal means I08 similar in construction to that described for thewithdrawal of the liquid may be positioned at the top or near the top ofthe container.

The Walls of the flexible envelope I may be constructed of any flexiblematerial which is impervious to gas and liquids and which is notdeleteriously acted upon by hydrocarbons and sim ilar fuels. Varioussynthetic rubber substitutes such as neoprene or duprene aresatisfactory in this respect. A very advantageous form of constructionof the flexible wall material is shown in Fig. 3a.. The wall thereillustrated in cross-section is constructed of inner and outer sheetsI619 and III) respectively havinga viscous or semi-plastic fluid IIItherebetween. I use for this plastic material compounds which are knownto the art of self-healing, i. e., they will exude into any accidentalperforations in the sheets IIIlor I89 and there harden so that theimperviousne'ss of the envelope as a whole is not injured by minorfailures. Ihe approximate shape of the inflated container may bespherical, cylindrical, or any special shape required for use in arestricted storage space. I find a cylindrical shape of relatively longaxial extension is advantageous in providing large capacity withoutexcessive wall tension, and if desired a plurality of such elongatedcylindrical flexible-Walled containers may be provided to increasefurther the ratio of capacity to skin tension.

Among the principal advantages of my flexible-walled, vapor inflatedcontainer are its ex-- treme lightness of construction and itsresistance to fatigue under conditions of continued vibration, thusmaking it well adapted for'aerohautical service. The advantages of thiscontainer are best realized'with fuels having only a model ately highvapor pressure, for example, from 16 to 25 pounds per square inch gauge.

One of the principal objects of my invention is to moderate the vaporpressure of a fuel having a large proportion of normally gaseousconstituents. One means of achievingthis object is to blend the normallygaseous constituents with normally liquid constituents adaptedto reducethe vapor pressure of the gaseous constituents, as disclosedmore fullyhereinafter.

Another means for reducing the vapor pressure of the fuel as maintainedin storage cons sts in the automatic control of the temperature thereofwhereby the vapor pressure of the fuel be maintained within limits whichpermit the use of relatively light Weight equipment for the storage andhandling of the fuel, this being a particularly important advantage inconnectie-n with the use of this fuel inaircraft or light weightautomotive vehicles.

In Fig. fl I have illustrated an automatic means for maintaining thevapor pressure of the fuel as stored within the storage vesselwithinprescribed upper limits. Referring particularly to Fig. 4, I20denotes a pressure-tight container thermally insulated on the exteriorby a coating of insulation I2I, The liquid withdrawal means includes apipe I22 arranged as a series of coils in heat exchange relationshipwith the liquid contents of the tank. One end of the coiled pipe I22communicates with a short riser I23 which is adapted to, receive theliquid contents of the tank and which has an end portion shaped as abeveled valve seat. A conical valve member are is arranged to cooperatewith the member 23 to form an adjustable valve means for thewithdrawalof the liquid fuel. The setting of this valve means is controlled by apressure responsive diaphragm I25 which acts through areversing leverlinkage I26 to restrict the valve opening when the pressures in thetankI20 are high, whereby the aperture afforded by the valve means isinversely proportional to the tank pressure.-

The other end of the coilmeans I22 communicates by means of a pipe I30with the suction of a pump, suitably a vane type pump as denoted by thenumeral I3I. The discharge from this pump, which represents thepressured fuel supplied the carburetor or other fuel utilizing means,may be passed through a heat exchanger or cooler I32 if desired.

The operation of this device is as follows. As the vapor pressure in thetank I28 increases due to an increase in temperature of the liquid fuelcontained therein, the pressure diaphragm I25 effects a partial closingof the valve means constituted by members I24 and I23. The withdrawnfuel is correspondingly subjected to asubstantial drop in pressure as ittraverses this valve means so that partial vaporization takes place inthe coil I22. The latent heat of vaporization is abstracted to a largedegree from the fuel remaining in theutank, whereby the latter iscooled. This condition endures until the liquid contents of the tankI253 have been cooled sufficiently that their vaporpressure is below apredetermined maximum value, which maximum value can be adjusted bymodifying the characteristics of the pressure diaphragm I25 or thelinkage between thisdiaphragm and the valve member I24. When the desiredpressure level is reached, the valve member I24 'will have beenretracted to a point Where further refrigerative effects are negligible.The fuel withdrawn from the pipe I30 during the refrigerating periodwill thus comprise a mixture of gas and liquid. This mixture ispreferably re-pressured by the pump I3I to a pressure sufiicient toagain completely liquefy the withdrawn fuel. If desired, the pressuresrequisite for this re-liquefaction can be considerably lowered bypassing the discharge ofthe pump through a cooler I32 which serves tocondense any vaporous constituents and abstract the heat ofcondensation.

This method of operation is essentially a method for removing excessiveheat from the stored high vapor pressure fuel by withdrawing the heatwith the withdrawn fuel. For static periodswhen no fuel is beingwithdrawn, further automatic internal refrigeration may be provided forby means of an adjustable pressure relief valve Hill which permits theescape of vapors when the pressure within the tank exceeds a valuecorresponding to the operative setting of the relief valve. This releaseof vapors causes further vaporization to take place within the tank,whereby the contents are chilled to the desired degree. The vapors thuspermitted to escape may be either wasted or passed to a low pressure,vapor storage vessel, or re-pressured, cooled, and condensed for returnto the storage vessel or. for immediate use as a liquid fuel as the casemay be.

The pressure relief valve may be rendered in- 'operative when. itsfunction is not desired by "closure ofa valve I 4| I may also employ abi-phase fuel system in connection with the automatic pressure controlin fuel storage tanks containing high vapor pressure fuels, whichlei-phase system employs the principle of withdrawing fuel from the gasand/ or liquid phase and regulating the proportions of gaseous andliquid fuels thus abstracted in accordance with the pressurein thestorage vessel, whereby the vaporous constituents are withdrawnpreponderantly at more elevatedpressures so that he attendantvaporization and internal refrigeration of the fuel thereby effected isemployed to reduce said high pressures.

This principle may be' used in connection with the operation of thecarburetor shown in Fig. 2

by supplying the needle valve 8! from the liquid phase in the fuelstorage tank, and supplying the needle valve 88 from the vapor phase inthe same tank, and by furthermore making the setting of the needle valve3! responsive to the pressures in the tank or in the fuel line, whichmay be readily done employing a conventional pressure responsive valve.The application of this principle is not limited, however, to use insuch a dual phase carburetor and in the embodiment shown in Fig. theprinciple is shown embodied in a device which ultimately supplies aconstant pressure, completely gasified fuel.

Referring to Fig. 5, an insulated storage tank ill!) is provided withwithdrawal lines l5] and 152 for the vaporous and liquid constituentsthereof respectively. The liquid flowing through the pipe i522 iscompletely gasiiied by a heating element before it is introduced into avalve box I54. The gaseous fuel withdrawn through the pipe l 5! isintroduced directly into the valve box Hi l. Ihe ginally gaseousmaterial and the originally liquid, now completely gasified, materialare introduced into the valve box I54; by means of valve ports 55 and556 respectively. The openings of these ports are reciprocallycontrolled by a douhie-ended valve member [51 the setting of which maderesponsive to a pressure bellows its by means of a fulcrumed linkage I59, The gaseous contents of the valve box lot are withdrawn through apipe 158 to a pressure reducing or constant pressure means means of apipe Hi2 to the ultimate destination (not indicated) of the constantpressure, completely gasified fuel.

The operation of this device is as follows. The fuel preferably containslittle or no non-volatile constituents. As long as the pressure withinthe fuel tank remains below the desired maximum operating pressure, thefuel is withdrawn largely as a liquid through the line I52, the valvemember 55'! being in its uppermost position to effect substantialclosure of the port I55. The pressure diaphragm or bellows l58 isadjusted to move the valve member i5! downwardly, opening the port I55and closing the port I56, when the pressure in the tank, which iscommunicated without substantial change to the valve box, exceeds thedesired maximum working pressure. Under these latter conditions the fuelwithdrawal is made largely from the vapor phase in the tank I50, wherebyvaporization is caused to take place within the tank to obtain thedesired internal refrigeration, thus again lowering the temperature anddependent pressure to within the desired operating range.

While I have shown the controlling valves in Figs. 4 and 5 as responsiveto pressure, I may also make use of temperature responsive controls inview of the known interdependence of vapor pressure and temperature.Such temperature controls should be set in accordance with the vaporpressure-temperature curve of the particular fuel employed in order tomaintain the pressure within the desired range.

By employing one or more of the above principies, the pressurerequirements of the fuel storage tank and fuel system generally may bevery greatly decreased, making possible a saving in construction weight.as Well as insuring the maintenance of safe operating pressures.

The fuels comprised in my invention are constituted by mixtures ofnormally gaseous constituents with normally liquid constituents and areintended for use primarily in liquid injection MI, and thence by fuelsystems such as those described above. In general, the proportion ofnormally liquid constituents is sufficientl high to effect a substantialreduction in vapor pressure of the normally gaseous constituents, and,on the other hand, the proportion of normally gaseous constituents issufficiently high to insure that the mixture retains in large degree theinherently advantageous characteristics of the normally gaseousconstituents. Apart from the question of relative volatility, thenormally liquid or relatively non-volatile constituents may alsocomprise such modifying agents as upper cylinder lubricants, knocksuppressors, and the like.

As normally gaseous constituents I employ primarily the lighterhydrocarbons such as methane, ethane, propane, and butane, theunsaturated hydrocarbons, propylene and butylene, and the like.

The normally liquid constituents in general comprise liquids which aremiscible with liquefled butane or propane or which are adapted todissolve substantial quantities of methane or ethane at relativelymoderate pressures. Another general characterization of these normallyliquid constituents is that they are substantially less volatiie thanthe normally gaseous constituents. As examples, I may mentionhydrocarbons boiling above 200 F., heavy ends from gasoline knowncommercially as naphthas, light lubricating oils such as are used forupper cylinder lubrication, and the like. I find that a naphtha havingan initial boiling point of ZOO-300 F. and an end boilin point notsubstantially in excess of lGO" F. constitutes a Very excellent normallyliquid constituent, although, if desired, these boiling ranges may bewidened to embrace most or all of the fractions normally contained ingasoline.

I may also emplo non-hydrocarbon materials as my normally liquidconstituent, particularly oxygenated materials such as alcohols,ketones, ethers, and the like, The normally liquid constituents maycomprise in whole or in part compounds which are adapted to supplylubrication to the upper cylinder walls or to increase flame propagationrate, or to widen the range of mixtures having proper ignitioncharacteristics, or to increase the'anti-knock rating, or to increasethe latent heat of vaporization, or to prevent carburetor icing, or toprevent ring sticking, or to decrease the total fuel cost, or to servein other known capacities for advantageously modifying thecharacteristics of the fuel. Since these fuels are to be stored underpressure and in the absence of air, I may readily employ constituentswhich are unstable in air, such as unrefined cracked gasoline which inthe presence of air tends to oxidize and form gum, or mixtures ofhydrocarbons and ethyl alcohol which tend to absorb water from air andseparate into two phases.

As indicated above, the best results are obtained by using a normallyliquid constituent which has a substantially lower vapor pressure thanthat of the normally gaseous constituent, for example, material havingan initial boiling point of or 200 F. The mixture thus obtained has asubstantial gap in boilins point from the normally gaseous constituentto the liquid constituent, which condition I find advantageous in atleast many instances.

When employing a hydrocarbon distillate as the normally liquidconstituent, I find in many instances that regard should be had for theend boiling point thereof, which for best results should new! not differgreatly from the end boiling points established as optimum forconventional gasolines, typically 400+30 F. Such a distillate may beeither a heavy naphtha, having an initial boiling point of 200 orhigher, or a typical gasoline fraction such as is readily availablecommercially. Very excellent high vapor pressure fuels may be made inaccordance with my invention by blending a minor proportion, e. g. 30%,of a commercial type gasoline with a major proportion, e. g. 70%, ofliquefied normally gaseous hydrocarbon such as butane and/ or propane.

I prefer to adjust the relative proportions of normally gaseous andnormally liquid constituents on the basis of the vapor pressure of theresulting mixture since the optimum percentage proportions may varyaccording to whether, for example, butane or methane is taken as thegaseous constitutent and according to the character of the liquidconstituent as well. I find, however, that the optimum composition ineach instance will have substantially the same vapor pressure and hencethis latter characteristic serves as a valuable criterion for adjustingthe composition.

My preferred range of vapor pressures is from to 30 pounds per squareinch gauge at 70 F. and within this range I find that about to poundsper square inch gauge at 60 F. represents the optimum vapor pressurecorresponding to the optimum composition with the constituentsconcerned.

I find that a mixed base fuel having a vapor pressure of from 10 topounds per square inch gauge or thereabouts, particularly from 15 to 25pounds per square inch at 60 F. contains sufficientof the gaseousconstituent to endow the mixture with advantageous characteristics. Acombustible mixture of air and such a fuel will not form condensates inthe intake manifold, will have a wide ignition range and a highanti-knock rating, will burn cleanly and without substantial formationof carbon, and will, when injected into the intake manifold, refrigeratethe charge sufficiently to give the effect of increased volumetricefficiency and increased density discussed hereinabove. I find,furthermore, that the atomization of the liquid fuel by the initial veryrapid vaporization of the gaseous constituent is displayed in completelyadequate degree by a mixed base fuel having substantially the indicatedoptimum vapor pressure.

I also find that by employing sufficient normally gaseous constituentsto bring the vapor pressure within the optimum range, the concentrationof completely vaporized fuel in the intake manifold downstream from thepoint of injection is insured to be sufficiently high to be asubstantial aid in the dispersion and/or vaporization of the relativelyless volatile constituents by effects of volume, velocity, and partialpressure.

While the indicated range of preferred vapor pressures is adequate tosecure the described advantages, .and is furthermore low enough .topermit the use of relatively lowpressure storage vesselS and fuelsystems, it is to be understood that my invention also extends to mixedbase fuels of still higher vapor pressures. That is particularly truewhen fixed gases, i. e., gases not readily liquefiable, typicallymethane and ethane, are to be used as the normally gaseous constituentsof the blend. Such blends will exhibit the desired characteristics whensufficient fixed gas has been added to bring the vapor pressure withinthe preferred range, but the weight per cent of fixedgas dissolved insuch a blend will remain relatively low. If itis chiefly desired to useas much fixed gas as possible, in View of its very low cost, thenrecourse may be had to much higher vapor pressure blends, e. g., blendshaving a vapor pressure of pounds per square gauge or higher at 60 F.,the increased mechanical costs for very high pressure fuel systems beingoffset by the lower cost of the fuel per se.

Mixed base fuels of the indicated composition have substantially all ofthe advantages incident to the use of completely gaseous fuels and atthe same time permit the co-use of some normally liquid constituent oflower quality or specific action. These advantages are obtained,moreover, without penalty of imposing high liquefying pressures on thefuel system since my fuels may be completely liquefiable at from 10 to30 pounds per square inch gauge :and preferably at about 20 pounds persquare inch gauge, which may be contrasted, for example, with the vaporpressure of liquid propane, which at 70 F. has a Vapor pressure of aboutpounds per square inch gauge. The advantageous characteristics of thesefuels are'fur-ther typified by the following examples:

Example 1.--Three volumes of a first structure gasoline were blendedwith seven volumes of liquefiecl gas consisting of 70% butane and 30%propane. The resulting blend had a vapor pressure of 24 pounds gaugeat60 F. When used in a carburetor similar to that shown in Fig. 2(cmploying a small proportion of primary fuel from the gaseous phase ofthe storage vessel), the effective knock rating was Well in excess of100. No knock could be obtained even when using a compression ratio of8.5 to l, and a20% increase in maximum power was obtained relative tothe maximum power obtainable using gasoline in a conventionalcarburetor. Relative to gasoline, fuel consumption was roughly the sameon a gallonage basis, substantially less on a weight basis.

It Was also found possible to change abruptly from idling toopenthrottle operation under full load without causing the stalling ormisfiring which this operation induces in conventional gasoline fueling.Formation of carbon and crankcase dilution were found to be negligible.

Example 2.Equal volumes of third structure gasoline (knock ratingapproximately 60) and butane were mixed to give a blend having a vaporpressure of approximately 15 pounds gauge at 60 F. The calculated knockrating of such a blend is about 72,, but in actual engine tests theeffective knock rating was found to be about 90, which enhancement wasdue, at least in part, to the inherent refrigeration of the combustiblecharge. In spite of the low manifold temperatures, high gasolinecontent, and relatively low vapor pressure, no indicationscould beobtained of manifold condensation.

Example 3.--1A blend of three parts of ethyl alcohol and seven parts ofliquefied gas (70% butane, 30% pro-pane) was. prepared and was found tohave a vapor pressure and operating characteristics similar to thosediscussed in Example 1.

Example 4.-A blend of four parts of a petroleum naphtha boiling from 200to 400 F, with 4.9 parts of butane and 2.1 parts of propane was found tohave a vapor pressure and operating characteristics intermediate thoseof Examples 1 and2.

Example 5.--Compressed ethane was introduced into gasoline until thegauge vapor pressure of the ethane-gasoline solution was (a) thirty 19pounds and (b) one hundred andfifty pounds. Both (a) and (b) showed'verysubstantially improved operating characteristics relative to thegasoline alone, the most pronounced'improvement being obtained with fuel(1)).

Several factors cooperate to make such fuels particularly advantageousfor use in aircraft. Inthe first place, their relatively moderate vaporpressure makes possible the use of relatively light storage vessels, ascontrasted, for instance, with the type of pressure cylinders requiredto store mixtures of butane and propane commercially available. In thesecond place, the weight of the total load including fuel is less thanwould correspond to a quantity of gasoline equivalent on a mileage basisand stored in conventional gasoline containers. This latter featurearises from the fact that the density of the liquefied, normally gaseousconstituent is very much less than that of gasoline although equalvolumes of my mixed base fuel and of gasoline will give about the samemileage due to the greater efficiency with which the former can be used.

It is to be understood that the details of the above examples areintended as illustrative rather than limitin and that variousmodifications of my invention may be practiced without departing fromthe essence of my invention as defined by the scope of the appendedclaims.

I claim as my invention:

1. Ina device for introducing high vapor pressure'fuel into an airpassage of an internal combustion engine, the combination of: a fuelmetering means; means for supplying liquid fuel under liquefyingpressure to said metering means; and

means for at least partially vaporizing the metered fuel in the absenceof air and in heat interchange relationship with the liquid fuel belllgsupplied to said metering means, whereby the high vapor pressure fuel iscooled ahead of said metering means to insure its complete liquiditywhen reaching said metering means.

2. In combination with an air passage of an internal combustion enginethrough which air is supplied to said engine: a two-phase carburetormeans for simultaneously supplying both liquid and gaseous fuels to saidpassage during normal operation of said engine; and means forautomatically stopping the supply of said liquid fuel to said passageduring idling conditions of said engine while continuing the supply ofsaid gase ous fuel during such idling conditions.

3. In a device for introducing fuel into an air induction passage of aninternal combustion engine, the combination of: means for continuouslydelivering a first portion of said fuel to said air passage and forvarying the rate of flow of said first portion of fue1 to besubstantially proportional to the mass rate of fiow of air in said airinduction passage, said means including a restricted orifice; means forcontinuously delivering the remaining portion of said fuel to said airpassage at all engine loads above idling; and means responsive to thepressure drop across said restricted orifice for varying the amount ofsaid remaining portion of said fuel delivered to said air passage to besubstantially proportional to the rate of fiow of said first portion offuel to said air induction passage.

4. In combination in a device for introducing fuel into the air passageof an internal combustion engine: means for delivering a first stream offuel to said air passage; means for delivering a second stream of fuelto said air passage; a

diaphragm operated valve for controlling the delivery of the secondstream of fuel to said air' passage; means including a restrictedorifice in said first stream to produce a valve-opening reduction inpressure on said diaphragm which increases the magnitude of reduction inpressure with increase in the rate of fiow of said first stream; andmeans including a restricted orifice in said'second stream to apply avalve-closing reduction in pressure on said diaphragm which increasesthe magnitude of reduction in pressure with increase in the rate of flowof said second stream, whereby the rate of flow of said second fuelstream is maintained substantially proportional to the rate of the firststream.

5. A method of obtaining a supercharging effect in the operation of aninternal combustion engine, which method includes the steps of:delivering a stream comprising a mixture of air and fuel to said engine;and introducing into said stream of admixed air and fuel before the sameis burned in said engine a pressure-liquefied fuel having a vaporpressure at F. above 10 lbs/sq. in. and containing substantialquantities of pressureliquefied normally gaseous constituents whichflash into vapor'at the pressure of said stream, said liquid fuelsubstantially instantaneously vaporizing in said stream to extracttherefrom the latent heat of vaporization. I

6. A method of supercharging an internal combustionengine, which m thodincludes the steps of: moving toward said engine in a confined space astream comprising air; and discharging into said stream droplets ofliquefied normally gaseous fuel in controlled amount to obtain a "directheat exchange between said fuel and said-air as said fuel vaporize's,said liquefied normally gaseous fuel having a vapor pressure above 10lbs/sq. in. at 60 F. and said stream of air being at a sufficiently lowpressure to insure substantially immediate flash-vaporization of thefuel in the liquid droplets discharged into said air stream.

'7. A method of forming a'fuel-air mixture for burning in a combustionspace, which method includes the steps of: delivering air to saidcombustion space; cooling said air by at least partially vaporizing aliquefied normally gaseous fuel in indirect heat-transfer relationshiptherewith; and thereafter "delivering said fuel to said combustionspace.

8. A method of operating an internal combustion engine, which methodincludes the steps of: delivering a stream of combustion air to saidengine; continuously introducinga gaseous fuel into said stream of airat one position; and continuously-introducing a liquid comprisingliquefied normally gaseous fuel intosaid stream at another position andin amount substantially proportional to the amount of-gaseous fuelcontinuously introduced into said stream of air.

9. A carburetion method, which method includes the steps of: moving aconfined stream of air through a passage; supplying to said stream ofair atdifferent axially-spaced positions a gaseous fuel and a liquidfuel; 'controllingthe supply of one of said fuels in response to theamount of air moving through said passage; and controlling the supply ofsaid other fuel in response to-variations in supply of said first-namedfuel and to make the supply of said other fuel substantiallyproportional to the supply of said one fuel.

10. A fuel system for internal combustion engines, comprising incombination: a pressure storage vessel adapted to contain a lower bodyof liquid fuel "andan'upper body of vaporized fuel means forming acharge-induction passageway for supplying admixed air and fuel to theengine; means communicating with the lower portion of said vessel fordelivering liquid fuel to said charge-induction passageway; meanscommunieating with the upper portion of said vessel near the top thereoffor delivering gaseous fuel to said charge-induction passageway andflow-control means responsive to the amount of one of said fuelsdelivered to said charge-induction passageway for controlling the amountof the other of said fuels delivered thereto.

11. In a carburetion device for the simultaneous use of two fuels in theformation of a combustible mixture, the combination of: means defining afirst restricted orifice for one of said fuels; means defining a secondrestricted orifice for the other of said fuels; means for supplying saidfuels respectively to said first and second orifices at proportionalpressures; walls defining an air passage; means for delivering said onefuel from said first restricted orifice to said air pasage; aflow-controlling valve means receiving the fuel from said second orificeand delivering same to said air passage; and means responsive to thepressure of said first fuelat a position beyond said first orifice andresponsive to the pressure of said second fuel beyond said secondorifice for regulating said flow-controlling valve means.

12. In a carburetion device for the simultaneous use of gaseous andliquid fuels, the combination of means defining a first restrictedorifice for said gaseous fuel; means defining a second restrictedorifice for said liquid fuel; means for supplying gaseous and liquidfuels respectively to said first and second orifices at proportionalpressures; walls defining an air passage; means for delivering saidgaseous fuel from said first restricted orifice to said air passage inamount substantially proportional to the mass rate of flow of airtherethrough; means for delivering liquid fuel from said secondrestricted orifice to said air passage; and means responsive to theamount of gaseous fuel delivered to said air passage for controlling theamount of said liquid fuel delivered to said air passage.

13. In a carburetion system, the combination of: walls defining an airpassage through which moves a stream of air; a tubular member extendinginto said air passage for discharging fuel into said air to form acombustible mixture; a flowregulating valve means providing intake anddischarge sides, said discharge side communicating with the interior ofsaid tubular member; means for delivering liquefied normally gaseousfuel to said intake side of said flow-regulating valve means underpressure, said means including a fuel-supply passage and an orificetherein across which a pressure drop is developed by fiow of said fueltoward said intake side of said flow-regulating valve means; and meansfor increasing and decreasing the amount of said fuel dischargingthrough said flow-regulating valve means in response to an increase anddecrease in the amount of air flowing in said air passage, said normallygaseous fuel expanding and cooling in the absence of air upon flowthrough said flow-regulating valve means to cool said tubular member anddischarging from said tubular member into said air stream while stillcomprising in part droplets of liquefied normally gaseous fuel whichsubstantially instantaneously vaporize in said air stream to cool same,said fuel supply passage providing a portion upstream from said orificeand extending in heat-transferring relationship with the cooled tubularmember to pre-cool said fuel at a position ahead of said orifice toinsure complete liquidity of said fuel upon delivery to said orifice.

is. In a carburetion system for introducing fuel into an air passagethrough which a stream of air is moving, the combination of: a casing; adiaphragm means in said casing and cooperating therewith in definingfirst and second chambers separated by said diaphragm means; a meteringorifice communicating with said first chamber; a metering orificecommunicating with said second chamber; means for supplying two fuelstreams respectively to said metering orifices at substantiallyequalpressures for flow respectively into said first and second chambersthrough said metering orifices whereby each fuel stream undergoes a dropin pressure during flow through its metering orifice, the reducedpressures acting on said diaphragm means; means for supplying fuel fromsaid first chamber to said air passage in amount increasing anddecreasing respectively with an increase and decrease in the amount ofair flowing in said air passage; means for conducting fuel from saidsecond chamber to said air passage to mix with the air flowing in saidpassage, said means including a flow-regulating valve means; and meansfor operatively connecting said flow-regulating valve means and saiddiaphragm means in a manner to move said valve means toward a more openposition upon increase in absolute pressure in said second chamber andtoward a more closed position upon increase in absolute pressure in saidfirst chamber.

15. In a carburetion system for forming a fuelair mixture by use of fueldrawn from an enclosed storage vessel containing a body of liquid fuelin the lower end thereof and a superimposed body of gas in the upper endthereof in contact with said body of liquid fuel, the combination of:means forming an air induction passage through which moves a stream ofair; means communieating with the upper end of said enclosed storagevessel for conducting a stream of gas to said air induction passagewhereby the source pressure of said gas is the same as the pressure onsaid liquid fuel in said storage vessel; means for varying the flow ofsaid gas to said air induction passage to be substantially proportionalto the mass rate of flow of said stream of air moving through said airinduction passage; fuel-delivery means communicating between the lowerportion of said enclosed storage vessel and said air induction passagefor delivering a stream of fuel to said air induction passage; and meansassociated with said fueldelivery means for maintaining the flow of saidfuel to said air induction passage substantially proportional to theflow of said stream of gas to said air induction passage.

16. In a carburetion system for forming a fuelair mixture from fueldrawn from an enclosed storage vessel containing a body of liquid fueland a superimposed body of gas comprising fuel vapor, the combinationof: means forming an air induction passage through which moves a streamof air; means for delivering a stream of gas from said vessel to saidair induction passage at a rate substantially proportional to the massrate of fiow of air through said air induction passage, said meansincluding a restricted orifice across which a pressure drop existsbecause of the flow of said stream of gas therethrough; means fordelivering to said air induction passage a stream of fuel drawn fromsaid vessel and including another restricted orifice across which apressure drop exists because of the flow of said fuel and including anadjustable control valve for controlling the flow of said fuel into saidair induction passage, said stream of fuel flowing through saidadjustable control Valve after passing through said other restrictedorifice; and means for automatically adjusting said control valve tomaintain substantially proportional the pressure drops across saidrestricted orifices.

17. In a :carburetion system, the combination of: means forming an airinduction passage through which moves a stream of air; two restrictedorifices each providing an entrance side and. an exit side; means fordelivering separate fuel streams at substantially equal pressurerespectively to the entrance sides of said restricted 24 orifices toestablish pressure drops across said orifices varying with the rate offuel flow therethrough; a pressure-responsive valve providing a movablemember, the pressures on the exit sides of said orifices beingrespectively transmitted to opposite sides of said movable member; meansfor supplying the fuel stream flowing through one orifice to said airinduction passage at a rate varying with the mass rate of air 'flowtherethrough; and means for supplying the fuel flowing through the otherorifice to said air induction passage through said valve therebycontrolling the rate of supply of this fuel.

ALBERT G. BODINE.

